usb: typec: tcpm: Ignore Vsafe0v in PR_SWAP_SNK_SRC_SOURCE_ON state

In PR_SWAP_SNK_SRC_SOURCE_ON state, Vsafe0v is expected as well so do
nothing here to avoid state machine going into SNK_UNATTACHED.

Fixes: 28b43d3d ("usb: typec: tcpm: Introduce vsafe0v for vbus")
Cc: stable <stable@vger.kernel.org>
Reviewed-by: Badhri Jagan Sridharan <badhri@google.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Kyle Tso <kyletso@google.com>
Link: https://lore.kernel.org/r/20210615173206.1646477-1-kyletso@google.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/typec/tcpm/tcpm.c

@@ -5212,6 +5212,7 @@ static void _tcpm_pd_vbus_vsafe0v(struct tcpm_port *port)
 		}
 		break;
 	case PR_SWAP_SNK_SRC_SINK_OFF:
+	case PR_SWAP_SNK_SRC_SOURCE_ON:
 		/* Do nothing, vsafe0v is expected during transition */
 		break;
 	default: